With recent development of a semiconductor technology, use of a high-efficiency light emitting diode (LED) is spreading. The LED is being applied to various fields of light emitting devices, such as a backlight unit of a display device, an incandescent lamp, a fluorescent lamp, and a street lamp.
In a light emitting device such as a lamp including the LED, a dead zone in which light may not reach may be generated according to a beam angle of the light. The dead zone of light may directly affect light emission quality. Accordingly, there has been a steady demand for research to prevent generation of the dead zone of light.